Titanium alkylphosphate functionalised mesoporous silica for enhanced uptake of rare-earth ions

Zhang, Wenzhong; Avdibegović, Dženita; Koivula, Risto; Hatanpää, Timo; Hietala, Sami; Regadío, Mercedes; Binnemans, Koen; Harjula, Risto

doi:10.1039/c7ta08127h

Cited by 21 publications

(14 citation statements)

References 41 publications

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“…Previously, we reported a group of titanium(IV) alkyl-phosphate grafted silica materials that retain Ln 3+ in a solvating extraction manner. 21 The addition of nitrate salts significantly enhanced the uptake of Nd 3+ and Dy 3+ on these grafted materials, thereby suggesting that the uptake mechanism follows eq 4 . However, the addition of 5 M NH 4 NO 3 inhibited the Ln 3+ uptake on the TiP_0:1 material ( Figure S3 ).…”

Section: Results and Discussionmentioning

confidence: 91%

“… 16 − 20 Recently, we have shown that titanium alkyl-phosphate functionalized mesoporous silica possesses solvating extraction capability. 21 The surface alkyl chains linked to titanium phosphate moieties mimic the structure of tri- n -butyl phosphate (TBP) and hence form complexes with Ln nitrates. However, these materials seem not to be perfect candidates for intralanthanide separation because of the similar complex formation constants across the Ln series.…”

Section: Introductionmentioning

confidence: 99%

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Intralanthanide Separation on Layered Titanium(IV) Organophosphate Materials via a Selective Transmetalation Process

Zhang

Hietala

Khriachtchev

et al. 2018

ACS Appl. Mater. Interfaces

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The lanthanides (Ln) are an essential part of many advanced technologies. Our societal transformation toward renewable energy drives their ever-growing demand. The similar chemical properties of the Ln pose fundamental difficulties in separating them from each other, yet high purity elements are crucial for specific applications. Here, we propose an intralanthanide separation method utilizing a group of titanium(IV) butyl phosphate coordination polymers as solid-phase extractants. These materials are characterized, and they contain layered structures directed by the hydrophobic interaction of the alkyl chains. The selective Ln uptake results from the transmetalation reaction (framework metal cation exchange), where the titanium(IV) serves as sacrificial coordination centers. The “tetrad effect” is observed from a dilute Ln3+ mixture. However, smaller Ln3+ ions are preferentially extracted in competitive binary separation models between adjacent Ln pairs. The intralanthanide ion-exchange selectivity arises synergistically from the coordination and steric strain preferences, both of which follow the reversed Ln contraction order. A one-step aqueous separation of neodymium (Nd) and dysprosium (Dy) is quantitatively achievable by simply controlling the solution pH in a batch mode, translating into a separation factor of greater than 2000 and 99.1% molar purity of Dy in the solid phase. Coordination polymers provide a versatile platform for further exploring selective Ln separation processes via the transmetalation process.

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Section: Results and Discussionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Intralanthanide Separation on Layered Titanium(IV) Organophosphate Materials via a Selective Transmetalation Process

Zhang

Hietala

Khriachtchev

et al. 2018

ACS Appl. Mater. Interfaces

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“…Now, extraction kinetics were investigated ( Figure 6 a), and the data clearly show that equilibrium is reached within only a few minutes with the lanthanides (3+), which is much faster than for other investigated systems, including commercial resins. 16 , 19 , 30 , 58 − 60 On the other hand, the uptake of scandium (3+) significantly increases with the extraction time, and after 1 h, no residual scandium (3+) is present in the solution. To further characterize the adsorption process and high affinity of the KIT-6-N-FGDA material toward scandium ions, adsorption experiments were performed with an initial concentration of REEs ranging from 5 to 300 μg L –1 , and Langmuir and Freundlich adsorption models were used to fit the experimental data ( Table S4 ).…”

Section: Results and Discussionmentioning

confidence: 99%

Understanding Selectivity of Mesoporous Silica-Grafted Diglycolamide-Type Ligands in the Solid-Phase Extraction of Rare Earths

Florek

Larivière

Kählig

et al. 2020

ACS Appl. Mater. Interfaces

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Rare earth elements (REEs) and their compounds are essential for rapidly developing modern technologies. These materials are especially critical in the area of green/sustainable energy; however, only very high-purity fractions are appropriate for these applications. Yet, achieving efficient REE separation and purification in an economically and environmentally effective way remains a challenge. Moreover, current extraction technologies often generate large amounts of undesirable wastes. In that perspective, the development of selective, reusable, and extremely efficient sorbents is needed. Among numerous ligands used in the liquid–liquid extraction (LLE) process, the diglycolamide-based (DGA) ligands play a leading role. Although these ligands display notable extraction performance in the liquid phase, their extractive chemistry is not widely studied when such ligands are tethered to a solid support. A detailed understanding of the relationship between chemical structure and function (i.e., extraction selectivity) at the molecular level is still missing although it is a key factor for the development of advanced sorbents with tailored selectivity. Herein, a series of functionalized mesoporous silica (KIT-6) solid phases were investigated as sorbents for the selective extraction of REEs. To better understand the extraction behavior of these sorbents, different spectroscopic techniques (solid-state NMR, X-ray photoelectron spectroscopy, XPS, and Fourier transform infrared spectroscopy, FT-IR) were implemented. The obtained spectroscopic results provide useful insights into the chemical environment and reactivity of the chelating ligand anchored on the KIT-6 support. Furthermore, it can be suggested that depending on the extracted metal and/or structure of the ligand and its attachment to KIT-6, different functional groups (i.e., C=O, N–H, or silanols) act as the main adsorption centers and preferentially capture targeted elements, which in turn may be associated with the different selectivity of the synthesized sorbents. Thus, by determining how metals interact with different supports, we aim to better understand the solid-phase extraction process of hybrid (organo)silica sorbents and design better extraction materials.

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“…Regarding the inclusion of selective ligand systems, Zhang et al . recently reported mesoporous MCM‐41 silica materials functionalized by titanium alkylphosphate using a solution‐based layer‐by‐layer deposition route for enhanced uptake of rare earth ions . The overall grafted structure was inspired by the LLE extractant tri‐ n ‐butyl phosphate (TBP) (Figure ).…”

Section: Recent Progress In Spe Of Rees Using Functionalized Mesoporomentioning

confidence: 99%

Recent Advances in the Separation of Rare Earth Elements Using Mesoporous Hybrid Materials

Florek

Larivière

et al. 2018

The Chemical Record

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Over the past decades, the need for rare earth elements (REEs) has increased substantially, mostly because these elements are used as valuable additives in advanced technologies. However, the difference in ionic radius between neighboring REEs is small, which renders an efficient sized‐based separation extremely challenging. Among different types of extraction methods, solid‐phase extraction (SPE) is a promising candidate, featuring high enrichment factor, rapid adsorption kinetics, reduced solvent consumption and minimized waste generation. The great challenge remains yet to develop highly efficient and selective adsorbents for this process. In this regard, ordered mesoporous materials (OMMs) possess high specific surface area, tunable pore size, large pore volume, as well as stable and interconnected frameworks with active pore surfaces for functionalization. Such features meet the requirements for enhanced adsorbents, not only providing huge reactional interface and large surface capable of accommodating guest species, but also enabling the possibility of ion‐specific binding for enrichment and separation purposes. This short personal account summarizes some of the recent advances in the use of porous hybrid materials as selective sorbents for REE separation and purification, with particular attention devoted to ordered mesoporous silica and carbon‐based sorbents.

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Titanium alkylphosphate functionalised mesoporous silica for enhanced uptake of rare-earth ions

Abstract: Solid-phase adsorbents for rare-earth ions are prepared by covalently binding organophosphate ligands on mesoporous silica via a versatile metal(iv)–O–P linkage.

Cited by 21 publications

References 41 publications

Intralanthanide Separation on Layered Titanium(IV) Organophosphate Materials via a Selective Transmetalation Process

Intralanthanide Separation on Layered Titanium(IV) Organophosphate Materials via a Selective Transmetalation Process

Understanding Selectivity of Mesoporous Silica-Grafted Diglycolamide-Type Ligands in the Solid-Phase Extraction of Rare Earths

Recent Advances in the Separation of Rare Earth Elements Using Mesoporous Hybrid Materials

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